[jritt@essex]

Below are two videos we produced on planning brake upgrades. Also, several years ago I wrote a basic brake upgrade guide on a different forum. Everything in that article applies to the M2. Hopefully these are helpful.

Videos

High Performance Brake Upgrade Guide

How to Plan for Future Brake Needs

Basic Brake Upgrade Guide

Daily Driver

If you never plan to do anything with your car other than drive it to work every day, there’s a solid chance you’ll be perfectly happy with the OEM brakes as delivered. Just about every modern car today has decent brakes, with far superior technology and performance vs. the cars our parents drove when we were kids. OEM brakes are designed for safety above all else. Any and all other considerations are secondary:

• Shortest stopping distance possible- Every once in a while, a kid chases ball into the road, or a deer jumps from the trees at an inopportune moment. The goal is to stop the car in the shortest possible distance to avoid a collision. The basic brake components are selected to achieve that goal based on the vehicle layout (RWD, FWD, etc.), weight, power, tires, etc.

• Stability- Inclement weather, limited driver skill, and chance all create road conditions that negatively impact a vehicle’s stability. Modern brake systems are designed to maintain as much stability under as many conditions as possible. ABS, traction control, and stability control systems all allow a driver to turn while braking, and help keep the car pointed in the desired direction. These systems also contribute to the point above, getting the car stopped and safe as quickly as possible.

• Repeated stops at max load- Manufacturers know their cars will be driven in rush-hour traffic, filled to the brim with gear from a local big box store, and/or possibly towing something at the vehicle’s max recommended load rating. Under those conditions, the car needs to be able to stop repeatedly in an acceptable manner.

Achieving the above objectives are sufficient for most of the cars on the road. For a specialized sports car, the manufacturer obviously goes a bit above and beyond these essentials. Factors such as pedal feel, pedal travel, pad compound feel, fade resistance under heavier than normal use, etc. all come into play. The manufacturer addresses these issues to make their car a competitive performer in the market, all while attempting to manage their costs as tightly as possible.

If your primary objective with your car is to safely take you from one place to another, you’ll be fine with leaving your stock brakes alone.

Spirited Street Driving

Enthusiasts tend to be a little tougher on equipment than ‘non-car’ people. They accelerate, turn, and brake harder on a regular basis, and they have higher performance expectations. Aggressive driving on back roads, canyons, etc. puts more heat into the brake system than running errands ever could. While manufacturers expect a sports car to be driven harder than a minivan, exactly how much harder leaves a lot of room for interpretation. Your idea of being tough on brakes may differ vastly from the engineers’ thoughts on the subject. Below is a list of upgrades that can be considered for aggressive street driving, in order of importance:

• High Performance Brake Pads- Performance pads will be your number one upgrade for improving brake feel and performance if you plan to drive your car hard on the street. I’ve written an in-depth article on how to choose the proper pads for your needs, so please read that article to learn more about pad selection.

• Slotted/Drilled Discs- If you upgrade your pads and still feel like you’re not getting enough bite out of them, you may want to consider slotted or drilled discs.

• Slotted discs provide more leading edges for a pad to bite into vs. a plain-face disc, and allow for pad material and water to evacuate the pad/disc interface. They are marginally more prone to cracking than plain face discs, but the added performance of slotted discs is worth the tradeoff to most enthusiasts (assuming the slot pattern is done correctly).

• Drilled discs, regardless of whether the holes are cast in or drilled after the casting process, are more prone to cracking than plain face or slotted discs. They do provide even more leading edges for pad bite, and a slight weight reduction. They also look snazzy.

• Slotted and drilled discs will wear your pads out more quickly than plain face discs. All of those leading edges assist with bite, but also increase wear rates.

• Holes and slots will also make more scraping and whirring noises than plain face discs, so there are some NVH (Noise Vibration Harshness) tradeoffs as well.

• Stainless Steel Brake Lines- While most people won’t notice a tremendous difference under street driving conditions, SS lines can enhance pedal feel, offer greater protection against road debris, and offer a slightly faster reaction time for brake activation.

• High Performance Brake Fluid- It is highly unlikely that you’ll boil your brake fluid under aggressive street driving. The more likely scenario is that you’ll only need to flush your brake fluid at regular service intervals. When you do, it never hurts to go with a slightly higher spec than stock if you plan to drive your car hard off the beaten path.

AutoX

Autocross presents a unique challenge for your car's brakes. Depending on the course layout, the amount of pad heat generated may not be any greater than stop-and-go traffic driving. Many times you never get out of second gear, which means speeds are generally limited to roughly 60 mph or less. Additionally, the flowing nature of a well-designed autocross course means that you don't always scrub off a tremendous amount of speed entering each brake zone. More often than not, you're trail-braking as you approach the apex of the corner, rather than standing on the brakes in a straight line. Therefore, precise control and feedback is what you're looking for in your brakes. Here are some brake upgrades to consider if you autoX your car:

• High Performance Brake Pads- As I discuss at length in my pads article, you’ll want a brake pad with good cold bite, predictable torque response, good all-weather performance, and a simple bed-in procedure.

• Slotted/Drilled Discs- Braking feel is extremely important in autocross, so for many drivers, slotted or drilled discs are worth the investment for the added touch they impart. Wear rates and NVH are secondary concerns when you’re fighting for every hundredth of a second. Additionally, drilled discs in particular can offer a tangible weight reduction, which can be critical in AutoX.

• Stainless Steel Brake Lines- As with discs, every little bit of added feel can mean the difference between winning or losing in a tightly contested AutoX. As such, properly made SS lines are a no-brainer upgrade with no downside.

• High Performance Brake Fluid- While fade isn’t typically an issue at AutoX, your increased maintenance and continual setup changes will mean that you’re under the car tinkering with your brakes more than you would be if you were only driving it on the street. As such, keeping some high quality brake fluid in the car as added insurance never hurts, nor does a good bleed for maintaining a firm and sensitive brake pedal.

• Two-piece Brake Discs- Unsprung weight is the devil to the avid autocrosser. You should always be looking to maximize weight reduction within the boundaries of the rules (or outside those boundaries if you’re really clever at cheating). Weight reduction in the wheels/brakes/suspension area is particularly beneficial to all aspects of acceleration, turning, and braking, which is the core of autoX. Two piece discs can in some cases offer substantial weight savings. Aftermarket two-piece discs will have aluminum hats that are lighter the stock iron pieces, and their overall construction and vane structure may offer further weight savings. Since you probably won’t be burning your discs up at a rapid rate, the initial cost of a two-piece disc may be worth the weight loss (commonly $600-$1000 per pair). Definitely check the price of replacement iron before making the commitment however. You will eventually have to change the discs since they are a wear item. Also, keep the size of the disc in mind. A larger than stock 2-piece disc may actually weigh more than the OEM units. Also, the larger the diameter of the disc, the greater the moment of inertia, which makes it more difficult to spin the disc from rest.

• Caliper Upgrade- A caliper-only upgrade could be a viable weight reduction option if the calipers are designed to work properly with the OEM master cylinder and discs. Again, the calipers must be sized properly, or you will be hurting your car's performance more than helping it!

• Aluminum, fixed-piston, opposed racing calipers tend to weigh less than OEM street calipers. For example, the OEM four piston front M2 caliper weighs 8 lbs., while the AP Racing CP9660 Radi-CAL weighs just over 6 pounds, despite having two extra pistons!

• However, slapping the calipers from a different vehicle on the FT86 can be a recipe for problems. While the parts may technically bolt onto the car, the actual performance may actually be significantly worse than stock. The main reason for this being improper brake bias. I will address this issue several more times throughout this article.

• Assuming bias is correct, in addition to a solid weight reduction, fixed piston racing calipers tend to offer substantially better feel, modulation, and a faster response than the OEM units due to enhanced stiffness. They are also superior at rejecting heat due to stainless steel pistons, high temperature seals, and no dust boots. Anti-knockback springs help keep a firm pedal after a series of S-turns, and an anodized finish won't burn up and change colors like a painted one.

• Aftermarket calipers may also offer a much wider range of pad selection, and the opportunity to increase pad volume and/or thickness.

• Big Brake Kit/Complete Competition Brake System- A complete brake system could be beneficial in AutoX for several reasons:

• Feel- Far stiffer, opposed piston racing calipers can offer dramatic changes in brake pedal feel and modulation. Some highly competitive types will find it worth the price of entry for this reason alone.

• Brake Balance/Bias- Getting the proper balance is very important for AutoX, and is closely related to the feel point above. If the piston sizes and disc diameter are not chosen carefully and properly (assuming you won’t be touching your OEM master cylinder), you will likely hurt your performance rather than help it. Increased (longer) stopping distances (the opposite of what you want), long brake pedal travel, and poor brake pedal feel are just some of the potential negatives of a poorly engineered system.

• Weight- Many complete brake kits shave weight over the stock setup. Even if the stock components and aftermarket components are the same physical dimensions, the aftermarket setup will be lighter 9 times out of 10. As an added bonus, the optimized components can offer a host of benefits if you also track your autoX car. On the other hand, if you add a system with extremely large discs and a huge eight piston caliper, you may be adding unnecessary unsprung weight and rotational mass to the car, and actually hurting your performance in autoX.

HPDE (High Performance Drivers Education)/Time Trial

On a road course, you will always put more heat into your brake system than you will on the street or at an autoX. Please reread that sentence! HPDE is really the first venue I've mentioned thus far where battling heat becomes the critical element in having an effective and reliable brake system.

One of the most interesting aspects of HPDE is the wide range of speeds and driver ability across run groups. As such, it's difficult to recommend a blanket brake solution for an M2 driven at a HPDE. As more and more people modify and drive these cars on tracks, we'll begin to get a better idea of what the typical and maximum brake demands will be. After countless discussions with customers on this topic over the years, I believe there a few key considerations when upgrading your brakes for an HPDE or Time Trial: Driver experience, track layout, vehicle configuration/modification, and tire choice. A careful examination of these factors in your personal situation should help guide you towards an acceptable brake solution. Keep in mind that all of these factors are related, and cannot be considered in isolation from one another.

• Driver experience- If you've never driven anywhere but the street, your first couple of trips to the track will most likely not tax your brake system too heavily, right? Not exactly. You being a complete track newbie won't necessarily protect your stock brakes from near total destruction. Novice drivers may be easier on the brakes because their corner exit speeds are lower, their terminal speeds entering brake zones are therefore lower, and there's less kinetic energy being transferred into heat during a given stop. That said, novice track drivers also tend to stab wildly at the brakes, stay on the brakes too long, oscillate between on and off brake, and do all sorts of other things one would never expect! The end result can be some serious brake punishment. It's impossible to say that a novice driver will be fine on stock brake pads based on track experience alone.

• Track layout- Long straights followed by tight turns mean your car is decelerating from a very high speed to a very low speed, creating a high energy stop. The distance between stops will also impact the heat retained in your brakes. If a particular track layout has a steady succession of medium straights and tight turns, your brakes don't have much time to cool between stops. That means heat will continually build. Flowing tracks with long sweepers are much easier on brakes (think Willow Springs (big track)). Look closely at the track(s) you'll be driving to determine how demanding they will be on your brakes.

• Vehicle configuration/modification- All else held equal, more massive, faster cars place a greater strain on the brake system in a brake zone. An Audi Allroad will require a much larger rotor as a heat sink than a Miata. If you strip 200lbs. out of your car (easier to accelerate), have a quality coilover system (higher cornering speeds), and add 50hp (greater acceleration), you're placing less demand on your brakes in terms of mass, but you'll need to slow down from higher speeds when entering turns.

• Tire choice- Tire choice is one of the single greatest factors in determining which brake setup will work for you on the track. The stickier the tire, the more brake you can use, and the more heat you will generate. More grip = more heat. If you're running the low grip OEM FT86 tires, or if it rains at an event, you won't be able to generate as much grip, and you won't tax your brakes as much.

So where does all of that leave us when upgrading your brakes for an HPDE or Time Trial? The critical point is, every modification you make to your car and the nut behind the wheel will change the demands on your brake system, and you must adjust accordingly. Just because you used a particular brake pad before, doesn't mean it will work again after you've installed your new turbo kit and Hoosiers. Chances are that after your 25th event, you'll be taxing your brakes very differently than you did during your first event. You'll be hitting higher speeds, entering and exiting corners faster and in a different way, and your car will likely have more grip and power than it did when you started (you'll also be much poorer, but likely happier ). If you typically run Limerock (a short track without many big braking zones), but decide to make a trip to Watkins Glen (a crazy fast track with huge brake demands), you need to reconsider how your brakes will be taxed. You must constantly evaluate the overall condition of your brake system, and not be afraid to try new brake setups as both you and your car evolve.

If you want to play it safe and not risk damage to the major components of your brake system, don't EVER drive an OEM pad on a road course. It may be more convenient and seem economical to run stock pads, but it will cost you time and money in the long run. There's also not much worse than wasted track time. When you're sitting in the pits watching your buddy rip down the front straight, and your stock pads are a steaming pile of dust lying inside your wheels, you'll be wishing you spent a couple hundred bucks and took the hour on Friday night to change your pads and bleed your fluid.

Hopefully that is helpful to some of you.